gearing on 3.0r

hello! would one of you lucky blokes with a new 3.0r be so kind as to tell us (me) what you're taching at 75 mph. for reference, the lgt is about 2800. many thanks!

hello! would one of you lucky blokes with a new 3.0r be so kind as to tell us (me) what you're taching at 75 mph. for reference, the lgt is about 2800. many thanks!

 

Must be nice! On my 5MT, I'm running 3,000 RPMs at 70. My old '98 w/ 4-spd auto also ran 3000 @ 70.

3.0R comes only in AUTO. right?

^ Yes.

Must be nice! On my 5MT, I'm running 3,000 RPMs at 70. My old '98 w/ 4-spd auto also ran 3000 @ 70.

 

+1. but on why doesn't my car run at 2800 rpm at 75. bosco

I don't know, but I just got through driving my mom's Avalon to Gulf Shores, AL and it's a 3.0 L V6. At 75 it was about 27-28 RPMs.

I don't know, but I just got through driving my mom's Avalon to Gulf Shores, AL and it's a 3.0 L V6. At 75 it was about 27-28 RPMs.

 

somebody help me. bosco

Whoa, whoa, WHOA! Guys! The speed limit is only 65 here in CA. Yikes! 75 and I might get a ticket...or worse...get passed by a bus! Actually, I'm still in my <1K break-in period and for that matter, am taking it very easy. However, once it's over, if you still haven't found your answer, I'll check back and let you know.

Whoa, whoa, WHOA! Guys! The speed limit is only 65 here in CA. Yikes! 75 and I might get a ticket...or worse...get passed by a bus! Actually, I'm still in my <1K break-in period and for that matter, am taking it very easy. However, once it's over, if you still haven't found your answer, I'll check back and let you know.

 

I'm guessing the 5EAT in the 3.0R has the same ratios as the GT.

 

On Cars101 I found this info:

http://www.cars101.com/subaru/legacy/legacy2005.html

 

It shows that the 2.5i 4EAT and 2.5 GT 5MT both have 4.111 final drive ratio, but the 2.5i 5MT has 3.90 and the GT 5EAT has 3.272.

 

They don't seem to have data on the 3.0R yet. I'll keep looking.

 

2.5i 5MT

1st 3.454

2nd 2.062

3rd 1.448

4th 1.088

5th .780

final 3.90

 

2.5 4EAT

1st 2.785

2nd 1.545

3rd 1.

4th .694

final reduction 4.111

 

2.5GT 5MT

1st 3.166

2nd 1.882

3rd 1.296

4th .972

5th .738

final reduction 4.111

 

2.5GT 5EAT

1st 3.540

2nd 2.264

3rd 1.471

4th 1.

5th .834

final reduction 3.272

I didn't dig deep enough. A few more clicks got me to the '08 Legacy page:

http://www.cars101.com/subaru/legacy/legacy2008.html

 

Oooh, they changed the 2.5GT ratios!

For '08

 

2.5i 5MT = 3.90

2.5 4EAT = 4.111

 

2.5GT 5MT = 3.90

2.5GT 5EAT = 3.083

 

Spec.B 6MT = 3.90

 

3.0R 5EAT = 3.272

Can you explain a little about why gear ratios make a difference? It's something that always confuses me. Thanks.

Can you explain a little about why gear ratios make a difference? It's something that always confuses me. Thanks.

 

Higher final drive ratio means more torque to the ground but lower top speed. Lower final drive means less torque down but higher top speed.

 

4.111 actually means 4.111:1 - That means the drive shaft spins 4.111 times for every revolution of the tires.

 

3.90 = 3.9 revolutions of driveshaft for 1 turn of the tires.

 

Higher final drive gives you higher RPM for any given speed than lower final drive ratio.

 

Hope that helps.

I think they changed it on the '07s as I'm definitely doing less than 3k at 70 MPH. I think it's a little more than 2600, which would probably put it at 2800 at 75.

I think they changed it on the '07s as I'm definitely doing less than 3k at 70 MPH. I think it's a little more than 2600, which would probably put it at 2800 at 75.

 

Here's the info shown on Cars101 for the 5MT. '06 & '07 are identical, but, if they increased the tire size, that would change the effective final drive ratio.

 

I did notice that the '07 Spec.B has taller tires than my '05. I have 18" wheels on, and 40-series tires give me the same outside diameter as stock. On the '07 Spec.B I saw at the dealer, it had 45-series tires, meaning taller sidewall (for the same tread width). If the GT also has taller tires, that would explain the difference.

 

'06

1st 3.166 2nd 1.882 3rd 1.296 4th .972 5th .738

final reduction 4.111

 

'07

1st 3.166 2nd 1.882 3rd 1.296 4th .972 5th .738

final reduction 4.111

 

'08

1st 3.166 2nd 1.882 3rd 1.296 4th 0.972 5th .738

final reduction 3.900

It appears that the 18" tires on the Spec.B and 3.0R have the same aspect ratio of 45 as the 17" tires. The tread width is the same as the 17" (215), so the sidewall height is the same, meaning the 18" tires have a larger outside diameter.

 

But only for the Spec.B and 3.0R.

 

Tire data:

 

'05 GT

215/45 ZR17

 

'06 GT

215/45 ZR17

 

'06 Spec.B

215/45 R18

 

'07 GT

215/45 ZR17

 

'07 Spec.B

215/45 R18

 

'08 GT

215/45 R17

 

'08 Spec.B

215/45 R18

 

'08 3.0R

215/45 R18

I don't know, but I just got through driving my mom's Avalon to Gulf Shores, AL and it's a 3.0 L V6. At 75 it was about 27-28 RPMs.

 

Are you friends with SLegacy99? He likes to tell stories about driving his mom's Lexus RX400h.

Checked on the way from work.

 

75MPH = 3,000 RPMs dead on.

Checked on the way from work.

 

75MPH = 3,000 RPMs dead on.

 

That's weird. Mine: 70mph = 3000 rpm.

 

I do have aftermarket 18" wheels and tires, but I've double-checked using GPS and my speedometer is dead on.

 

Maybe Cars101 is wrong?

hello! would one of you lucky blokes with a new 3.0r be so kind as to tell us (me) what you're taching at 75 mph. for reference, the lgt is about 2800. many thanks!

 

at 80 i am at 2800 rpm's...it's funny though. supposedly we have the exact same tranny.

at 80 i am at 2800 rpm's...it's funny though. supposedly we have the exact same tranny.

 

But you have taller tires. That probably accounts for the difference.

But you have taller tires. That probably accounts for the difference.

 

how do i have taller tires? i am bone stock outside of potenza 960a/s in stock sizes. NOTHING is different before or after tires.

 

 

 

the difference is the m/t vs the a/t. gearing for the manual is for accleration. the a/t is a nice hghway cruiser.

how do i have taller tires? i am bone stock outside of potenza 960a/s in stock sizes. NOTHING is different before or after tires.

 

 

the difference is the m/t vs the a/t. gearing for the manual is for accleration. the a/t is a nice hghway cruiser.

 

 

Based on the info I posted above, the 3.0R and Spec.B tires have a larger outside diameter/circumference from the GT tires, therefore, with the exact same transmission and final drive ratio, the 3.0R and Spec.B will be spinning slower RPMs for any given road speed.

 

Even though they appear similar by having similar measurements, i.e.: 215/45 R17 & 215/45 R18, the 45 is the aspect ratio. It's the ratio between tread width and sidewall height.

 

If you have the exact same aspect ratio, and the exact same tread width, an 18" tire will be taller than a 17" tire, 1 inch taller.

 

Circumference is Pi x D (3.14 times diameter):

I don't know the diameter of the tires, so I'll use the wheels instead, as an example:

 

17" x 3.14 = 53.38" That's the circumference.

18" x 3.14 = 56.52" You can already see the distance around the 18" wheel is greater.

 

Let's say your sidewall is 3". That means we add 6" (3 top, 3 bottom) to get tire size:

23 x 3.14 = 72.22"

24 x 3.14 = 75.36"

 

The circumference of the 18" tire is about 3 inches greater than the 17" tire.

 

So, on the GT, for every full rotation of the tire, you cover 72 inches of ground, on the Spec.B and 3.0R, in covering that same 72 inches, you're 3 inches short of a full rotation, since a full rotation would be 75 inches, which means your entire driveline is rotating slower than on the GT for the same actual speed.

 

Make sense?

Based on the info I posted above, the 3.0R and Spec.B tires have a larger outside diameter/circumference from the GT tires, therefore, with the exact same transmission and final drive ratio, the 3.0R and Spec.B will be spinning slower RPMs for any given road speed.

 

Even though they appear similar by having similar measurements, i.e.: 215/45 R17 & 215/45 R18, the 45 is the aspect ratio. It's the ratio between tread width and sidewall height.

 

If you have the exact same aspect ratio, and the exact same tread width, an 18" tire will be taller than a 17" tire, 1 inch taller.

 

Circumference is Pi x D (3.14 times diameter):

I don't know the diameter of the tires, so I'll use the wheels instead, as an example:

 

17" x 3.14 = 53.38" That's the circumference.

18" x 3.14 = 56.52" You can already see the distance around the 18" wheel is greater.

 

Let's say your sidewall is 3". That means we add 6" (3 top, 3 bottom) to get tire size:

23 x 3.14 = 72.22"

24 x 3.14 = 75.36"

 

The circumference of the 18" tire is about 3 inches greater than the 17" tire.

 

So, on the GT, for every full rotation of the tire, you cover 72 inches of ground, on the Spec.B and 3.0R, in covering that same 72 inches, you're 3 inches short of a full rotation, since a full rotation would be 75 inches, which means your entire driveline is rotating slower than on the GT for the same actual speed.

 

Make sense?

 

all you really have to do is go to http://www.discounttire..com they have a calulator for all the tires they sell some brands are different dimensions for the same size tire. they even tell you speedo error, distance traveled , etc. bosco

Based on the info I posted above, the 3.0R and Spec.B tires have a larger outside diameter/circumference from the GT tires, therefore, with the exact same transmission and final drive ratio, the 3.0R and Spec.B will be spinning slower RPMs for any given road speed.

 

Even though they appear similar by having similar measurements, i.e.: 215/45 R17 & 215/45 R18, the 45 is the aspect ratio. It's the ratio between tread width and sidewall height.

 

If you have the exact same aspect ratio, and the exact same tread width, an 18" tire will be taller than a 17" tire, 1 inch taller.

 

Circumference is Pi x D (3.14 times diameter):

I don't know the diameter of the tires, so I'll use the wheels instead, as an example:

 

17" x 3.14 = 53.38" That's the circumference.

18" x 3.14 = 56.52" You can already see the distance around the 18" wheel is greater.

 

Let's say your sidewall is 3". That means we add 6" (3 top, 3 bottom) to get tire size:

23 x 3.14 = 72.22"

24 x 3.14 = 75.36"

 

The circumference of the 18" tire is about 3 inches greater than the 17" tire.

 

So, on the GT, for every full rotation of the tire, you cover 72 inches of ground, on the Spec.B and 3.0R, in covering that same 72 inches, you're 3 inches short of a full rotation, since a full rotation would be 75 inches, which means your entire driveline is rotating slower than on the GT for the same actual speed.

 

Make sense?

 

yup. i thought the 3.0 came with 215-45-17's. still. at 75 and 2800 my gt is 80 at 2800.

all you really have to do is go to www.discounttire..com they have a calulator for all the tires they sell some brands are different dimensions for the same size tire. they even tell you speedo error, distance traveled , etc. bosco

 

 

or the all time fav...miata tire cal.